JEE Main 2026 · 2 Apr · Shift 1 · Physics Q32

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PhysicsSingle correct+4 / -1Question 32 of 75

A parallel plate air capacitor has a capacitance $C$ . When it is half filled as show in figure with a dielectric constant $K=5$ , the percentage increase in the capacitance is ________.

Parallel-plate capacitor with plate separation d (top plate +, bottom plate −); a dielectric slab with K = 5 fills the upper half, thickness d/2, across the full plate area; the lower half is air.

33.34

66.67

200

400

Answer and worked solution

Official answer: B

Two capacitors in series. Each half has gap $d/2$ , so $C_1=\dfrac{K\epsilon_0A}{d/2}=10C$ and $C_2=\dfrac{\epsilon_0A}{d/2}=2C$ .

Combination. $C'=\dfrac{10C\cdot2C}{12C}=\dfrac53C$ .

Increase. $\frac23=66.67\%$ .

(B)

Topics:Dielectrics Series and parallel combinations

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JEE Main 2026 · 2 Apr · Shift 1, Physics question 32